HBV may have another virion form in which the nucleic acid is composed of RNA, not DNA. The level of HBV RNA virion in serum may be associated with risk of HBV viral rebound after withdrawal of treatment, and therefore, a potential predictive biomarker to monitor the safe discontinuation of nucleot(s)ide analogues-therapy.

The clustered regularly interspaced short palindromic repeats (CRISPR)/associated nuclease (Cas) system is an efficient gene editing tool. In this study, it is found that both single guide RNA (gRNA) and Cas9 protein could be exported from the CRISPR/Cas9‐expressing cells by endogenous exosomes independently. Further experiments demonstrate that these naturally produced endogenous exosomes could be used as a vehicle to deliver the functional Cas9 and hepatitis B virus (HBV)‐specific gRNA to cut HBV DNA transfected in HuH7 cells or human papilloma virus (HPV)‐specific gRNA to cut the integrated HPV DNA in HeLa cells, respectively. In conclusion, this study indicates the potential of endogenous exosomes as a safe and effective delivery vehicle of the functional gRNA and Cas9 protein. Meanwhile, the endogenous exosomes‐mediated delivery of gene editing activity to adjacent and distant cells or tissues may further complicate the off‐target and safety concerns about the CRISPR/Cas9 system.

ObjectiveThis study was performed to explore the correlation between the characteristics of hepatitis B virus (HBV) quasispecies in HBV-infected pregnant women and the risk of immunoprophylaxis failure for their infants.DesignIn this prospective nested case–control study, the characteristics of HBV quasispecies in mothers whose infants were immunoprophylaxis success (control group) and those whose infants were immunoprophylaxis failure (case group) were analysed by the clone-based sequencing of full-length HBV genome and next-generation sequencing (NGS) of “a” determinant region, and were compared between the two groups.ResultsThe quasispecies characteristics including mutant frequency, Shannon entropy and mean genetic distance at amino acid level of “a” determinant region were significantly lower in case group than that in control group, using the full-length HBV genome clone-based sequencing assay. These results were confirmed by NGS assay. Notably, we discovered that the differences were also significant at nucleotide level by NGS assay. Furthermore, the risk of immunoprophylaxis failure could be predicted by analysing the three HBV quasispecies characteristics either at nucleotide level or at amino acid level of “a” determinant region, and the corresponding predictive values were tentatively set up.ConclusionsHBV quasispecies with a more complex mutant spectrum in “a” determinant region might be more vulnerable to extinct through mother-to-child-transmission (MTCT). More importantly, analysing HBV quasispecies characteristics in pregnant women with high HBV DNA load might be helpful to predict the high-risk population of immunoprophylaxis failure, and consequently provide accurate intervention against MTCT of HBV.

Cytotoxic chemotherapy drugs, including doxorubicin, can directly promote hepatitis B virus (HBV) replication, but the mechanism has not been fully clarified. This study investigated the potential mechanism underlying the cytotoxic chemotherapy‐mediated direct promotion of HBV replication. We found that HBV replication and regulatory factor X box 1 gene (RFX1) expression were simultaneously promoted by doxorubicin treatment. The amount of RFX1 bound to the HBV enhancer I was significantly increased under doxorubicin treatment. Furthermore, the activity of doxorubicin in promoting HBV replication was significantly attenuated when the expression of endogenous RFX1 was knocked down, and the EP element of HBV enhancer I, an element that mediated the binding of RFX1 and HBV enhancer I, was mutated. In addition, two different sequences of the conserved EP element were found among HBV genotypes A‐D, and doxorubicin could promote the replication of HBV harboring either of the conserved EP elements. Here, a novel pathway in which doxorubicin promoted HBV replication via RFX1 was identified, and it might participate in doxorubicin‐induced HBV reactivation. These findings would be helpful in preventing HBV reactivation during anticancer chemotherapy.

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